Treating inflammatory disorders by stimulation of the cholinergic anti-inflammatory pathway

ABSTRACT

Described herein are methods for treating a subject suffering from or at risk for a condition mediated by an inflammatory cytokine cascade, by electrically or mechanically stimulating vagus nerve activity in an amount sufficient to inhibit the inflammatory cytokine cascade.

CROSS REFERENCE TO RELATED APPLICATIONS

This patent application claims priority as a continuation-in-part ofU.S. patent application Ser. No. 11/318,075, filed Dec. 22, 2005, whichclaims priority to provisional patent application 60/639,332, field Dec.27, 2004. This patent application also claims priority to U.S.Provisional Patent Application Ser. No. 60/982,681, filed Oct. 25, 2007.

INCORPORATION BY REFERENCE

All publications and patent applications mentioned in this specificationare herein incorporated by reference in their entirety to the sameextent as if each individual publication or patent application wasspecifically and individually indicated to be incorporated by reference.

FIELD OF THE INVENTION

The methods, systems and devices described herein are directed totreatment of inflammatory disorders by appropriate and controlledstimulation of all or a portion of the cholinergic anti-inflammatorypathway.

BACKGROUND OF THE INVENTION

Vertebrates achieve internal homeostasis during infection or injury bybalancing the activities of pro-inflammatory and anti-inflammatorypathways. In many disease conditions, this internal homeostasis becomesout of balance. For example, endotoxin (lipopolysaccharide, LPS)produced by Gram-negative bacteria activates macrophages to releasecytokines that are potentially lethal (Tracey, K. J. et al., Science,234:470-74 (1986); Dinarello, C. A., FASEB J., 8:1314-25 (1994); Wang,H., et al., Science, 285:248-51 (1999); Nathan, C. F., J. Clin. Invest.,79:319-26 (1987)).

Inflammation and other deleterious conditions (such as septic shockcaused by endotoxin exposure) are often induced by pro-inflammatorycytokines, such as tumor necrosis factor (TNF; also known as TNF-α orcachectin), interleukin (IL)-1α, IL-1β, IL-6, IL-8, IL-18, interferon-γ,platelet-activating factor (PAF), macrophage migration inhibitory factor(MIF), and other compounds. Certain other compounds, for example highmobility group protein 1 (HMG-1), are induced during various conditionssuch as sepsis and can also serve as pro-inflammatory cytokines.Pro-inflammatory cytokines contribute to various disorders, notablysepsis, through their release during an inflammatory cytokine cascade.Inflammatory cytokine cascades contribute to deleteriouscharacteristics, including inflammation and apoptosis, of numerousdisorders.

Although the pro-inflammatory cytokines typically aid in protectingagainst invasive pathogens, failure to resolve the initial infection canresult in overproduction and spillage of cytokines into the systemiccirculation, causing shock and lethal tissue injury. Counter-regulatorymediators, including glucocorticoids and interleukin-10, function tolimit excessive pro-inflammatory responses. However, these humoral“anti-inflammatory” mechanisms can also predispose the host to secondaryinfections and increase overall morbidity and mortality.

It has recently been shown that the nervous system regulates systemicinflammation through an α7 nicotinic acetylcholine receptor(α7nAChR)-dependent vagus nerve pathway to the spleen, termed thecholinergic anti-inflammatory pathway (Huston J M, Ochani M,Rosas-Ballina M, et al., J Exp Med 2006; 203:1623-1628 (2006)). Thisanti-inflammatory pathway may form an inflammatory reflex, including thevagus nerve, the splenic nerve, the hepatic nerve, the facial nerve, andthe trigeminal nerve.

Electrical stimulation of the anti-inflammatory pathway (e.g., the vagusnerve or other portions of the anti-inflammatory reflex such as thesplenic nerve, the hepatic nerve, etc.) inhibits pro-inflammatorycytokine production and prevents tissue injury in experimental models ofsystemic inflammation. Such stimulation fails to regulatepro-inflammatory responses in α7nAChR-deficient or splenectomizedanimals, or following interruption of the common celiac vagus branches,indicating that the cholinergic anti-inflammatory pathway requiresspecific molecular, organ, and neural components.

Pharmacologic α7nAChR agonists may mimic the effects of stimulation, andadministration of these agents to mice with polymicrobial sepsisimproves survival and attenuates production of high mobility group box 1(HMGB1), a critical mediator of lethal sepsis. It is unclear, however,whether chronic vagus nerve stimulation can also improve survival duringlethal sepsis.

Furthermore, the components of the cholinergic anti-inflammatorypathway, such as the vagus nerve, also subsume a number of otherphysiological roles and functions. In particular, the vagus nerveactivation and/or inhibition is involved in regulating cardiac function(e.g., heart rate), larynx function, diaphragm activity (respiration),stomach (digestion) and includes both motor and sensory functions, aswell as being implicated in brain activity including consciousness.Thus, the stimulation of any portion of the cholinergicanti-inflammatory pathway, and particularly the vagus nerve, must beperformed specifically and precisely, in order to avoid disrupting orundesirably modifying any of these other functions.

Described herein are methods, systems and devices for specificallyregulating the cholinergic anti-inflammatory pathway by preciselyregulated and applied stimulation. In particular, described herein aremethods, systems and devices for treating inflammation by electricalstimulation that are sufficient to inhibit inflammation withoutsubstantially affecting heart rate or other cardiac parameters,digestion, respiration, or other biological systems regulated bycomponents of the inflammatory reflex such as the vagus nerve.

For example, the methods described herein provide methods for inhibitionof pro-inflammatory cytokine production and protection against the longand short-term effects of the pro-inflammatory cytokines.

SUMMARY OF THE INVENTION

In general, described herein are methods, systems and devices fortreating cytokine-mediated inflammatory conditions. These methods,systems and devices typically stimulate all or a portion of a patient'sinflammatory reflex (e.g., the vagus nerve), to inhibit inflammation,pro-inflammatory cytokine production or release, or the pro-inflammatorycytokine cascade. For example, the inhibitory stimulation describedherein includes extremely low duty-cycle stimulation, such asstimulation of the vagus nerve at levels that do not provoke othernon-immune, biological effects mediated by the vagus nerve (e.g., bloodpressure, heart rate, etc.). Also described is effective repeated and/orchronic stimulation of the vagus nerve. For example, the effectiveextremely low-intensity vagus stimulation, and particularly chronic (orrepeated) stimulation of the cholinergic anti-inflammatory pathway, mayinclude low or extremely low duty-cycle (e.g., less than 1%, less than0.01%, less than 0.001%, less than 0.0001%) stimulation of the vagusnerve to effectively inhibit or beneficially modulate inflammation orcytokine-mediated inflammatory conditions.

Using the methods and devices described herein, inflammatory disorderscan be treated in a subject by electrically stimulating the cholinergicanti-inflammatory pathway, including, without limitation, the vagusnerve. Surprisingly, it has also been discovered that the parameters ofan electrical signal sufficient to treat inflammatory disorders aresignificantly milder than the parameters previously shown to inhibit theinflammatory cytokine cascade. Thus, it has been discovered thatinflammatory disorders can be treated by an electrical signal having itscurrent or voltage significantly smaller than electrical signalspreviously shown to inhibit inflammation.

Described herein are methods of treating an inflammation in a patient.For example, the method may include the steps of: stimulating thepatient's vagus nerve with an electrical signal, wherein the signalvoltage is between about 0.01 Volt to 1 Volt, the pulse width is from0.1 ms to 5 ms; the signal frequency is from 0.1 Hz to 30 Hz; signalon-time is from 1 second to 120 seconds; and waiting for an off-time ofat least 2 hours before re-stimulating the patient's vagus nerve. Insome variations, the method may also include the step of monitoring oneor more non-inflammatory vagal efferent effects (e.g., heart rate, bloodpressure, heart rate variability, digestive processes) and modifying thestimulation so that it does not affect such parameters.

In some variations, the stimulation is transcutaneous stimulation of thevagus nerve. For example, the stimulation may be transdermal. In somevariations, the intensity of the stimulation (e.g., the voltage between0.01 and 1 V) is determined at the nerve. Thus the voltage applied tothe electrode(s) may be adjusted based on the attenuation through thetissue.

The off-time before the vagus nerve is re-stimulated may be from about 2hours to about 48 hours. In general “off-time” is the time between“stimulation-on” periods or burst of pulses. For example, a burst ofsignals at 30 Hz for 120 seconds may be followed by an off-time of 2 ormore hours. During the off-time, a controller for the system may belocked so that additional stimulation cannot be applied. In somevariations, the off-time before the vagus nerve is re-stimulated isbetween about 16 and about 30 hours.

The method may also include the step of monitoring the effect of thestimulation on inflammation in the patient. For example, the level of apro-inflammatory cytokine prior to stimulation may be determined, aswell as the level of a pro-inflammatory cytokine during/afterstimulation, and the levels may be compared. The intensity and/offrequency of stimulation may be adjusted based on the monitoring.

Also described herein are methods of treating inflammation in a patient,including the steps of: applying an electrode to a patient sufferingfrom or at risk for a chronic inflammatory disorder; stimulating thepatient's vagus nerve with an electrical signal from the electrode,wherein the signal voltage is from 0.01 Volt to 1 Volt, pulse width isfrom 0.1 ms to 5 ms; signal frequency is from 0.1 Hz to 30 Hz; signalon-time is from 1 second to 120 seconds; and waiting for an off-time ofat least 2 hours before re-stimulating the patient's vagus nerve.

As mentioned above, in some variations, the method may be transcutaneousstimulation.

The chronic inflammatory disorder treated may be selected from the groupconsisting of: appendicitis, peptic ulcer, gastric ulcer, duodenalulcer, peritonitis, pancreatitis, ulcerative colitis, pseudomembranouscolitis, acute colitis, ischemic colitis, diverticulitis, epiglottitis,achalasia, cholangitis, cholecystitis, hepatitis, Crohn's disease,enteritis, Whipple's disease, allergy, anaphylactic shock, immunecomplex disease, organ ischemia, reperfusion injury, organ necrosis, hayfever, sepsis, septicemia, endotoxic shock, cachexia, hyperpyrexia,eosinophilic granuloma, granulomatosis, sarcoidosis, septic abortion,epididymitis, vaginitis, prostatitis, urethritis, bronchitis, emphysema,rhinitis, pneumonitis, pneumotransmicroscopicsilicovolcanoconiosis,alvealitis, bronchiolitis, pharyngitis, pleurisy, sinusitis, influenza,respiratory syncytial virus infection, HIV infection, hepatitis B virusinfection, hepatitis C virus infection, disseminated bacteremia, Denguefever, candidiasis, malaria, filariasis, amebiasis, hydatid cysts,burns, dermatitis, dermatomyositis, sunburn, urticaria, warts, wheals,vasulitis, angiitis, endocarditis, arteritis, atherosclerosis,thrombophlebitis, pericarditis, myocarditis, myocardial ischemia,periarteritis nodosa, rheumatic fever, Alzheimer's disease, coeliacdisease, congestive heart failure, adult respiratory distress syndrome,meningitis, encephalitis, multiple sclerosis, cerebral infarction,cerebral embolism, Guillame-Barre syndrome, neuritis, neuralgia, spinalcord injury, paralysis, uveitis, arthritides, arthralgias,osteomyelitis, fasciitis, Paget's disease, gout, periodontal disease,rheumatoid arthritis, synovitis, myasthenia gravis, thyroiditis,systemic lupus erythematosis, Goodpasture's syndrome, Behcet's syndrome,allograft rejection, graft-versus-host disease, Type I diabetes,ankylosing spondylitis, Berger's disease, Reiter's syndrome andHodgkin's disease.

The off-time before the vagus nerve is re-stimulated may be from betweenabout 2 hours to about 48 hours. For example, the off-time before thevagus nerve is re-stimulated may be between about 16 and about 30 hours.

Also described herein are methods of treating inflammation in a patientincluding the steps of: implanting an electrode into a patient sufferingfrom a chronic inflammatory disorder; stimulating the patient's vagusnerve with an electrical signal from the implanted electrode, whereinthe signal voltage is from 0.01 Volt to 1 Volt, pulse width is from 0.1ms to 5 ms; signal frequency is from 0.1 Hz to 30 Hz; signal on-time isfrom 1 second to 120 seconds; and waiting for an off-time of at least 2hours before re-stimulating the patient's vagus nerve.

The chronic inflammatory disorder treated may be selected from the groupconsisting of: appendicitis, peptic ulcer, gastric ulcer, duodenalulcer, peritonitis, pancreatitis, ulcerative colitis, pseudomembranouscolitis, acute colitis, ischemic colitis, diverticulitis, epiglottitis,achalasia, cholangitis, cholecystitis, hepatitis, Crohn's disease,enteritis, Whipple's disease, allergy, anaphylactic shock, immunecomplex disease, organ ischemia, reperfusion injury, organ necrosis, hayfever, sepsis, septicemia, endotoxic shock, cachexia, hyperpyrexia,eosinophilic granuloma, granulomatosis, sarcoidosis, septic abortion,epididymitis, vaginitis, prostatitis, urethritis, bronchitis, emphysema,rhinitis, pneumonitis, pneumotransmicroscopicsilicovolcanoconiosis,alvealitis, bronchiolitis, pharyngitis, pleurisy, sinusitis, influenza,respiratory syncytial virus infection, HIV infection, hepatitis B virusinfection, hepatitis C virus infection, disseminated bacteremia, Denguefever, candidiasis, malaria, filariasis, amebiasis, hydatid cysts,burns, dermatitis, dermatomyositis, sunburn, urticaria, warts, wheals,vasulitis, angiitis, endocarditis, arteritis, atherosclerosis,thrombophlebitis, pericarditis, myocarditis, myocardial ischemia,periarteritis nodosa, rheumatic fever, Alzheimer's disease, coeliacdisease, congestive heart failure, adult respiratory distress syndrome,meningitis, encephalitis, multiple sclerosis, cerebral infarction,cerebral embolism, Guillame-Barre syndrome, neuritis, neuralgia, spinalcord injury, paralysis, uveitis, arthritides, arthralgias,osteomyelitis, fasciitis, Paget's disease, gout, periodontal disease,rheumatoid arthritis, synovitis, myasthenia gravis, thyroiditis,systemic lupus erythematosis, Goodpasture's syndrome, Behcet's syndrome,allograft rejection, graft-versus-host disease, Type I diabetes,ankylosing spondylitis, Berger's disease, Reiter's syndrome andHodgkin's disease.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a simplified block diagram of one variation of a stimulator(e.g., an electrical stimulus generator) suitable for applyingelectrical stimulation.

FIG. 2 shows one suitable location for vagus nerve stimulation (VNS)using an electric signal generator and electrodes implanted in thepatient's body.

FIG. 3 is an illustrative idealized electrical output signal waveformthat may be useful for clarifying relevant parameters of the stimulationsignal.

FIG. 4 is a bar plot illustrating the effect of the vagal electricalstimulation on endotoxemia as measured by a reduced percentage of serumTNF level.

FIG. 5 is a plot showing the effect of electrical VNS on TNF productionin LPS-challenged mice. Vertical axis indicates percent suppression ofTNF, horizontal axis indicates hours elapsed between the VNS stimulationand LPS challenge. The deviation of TNF suppression substantiallyexceeds the period of applied VNS.

FIG. 6 is a plot that shows an arthritis score in rats as a function ofa number of days post collagen immunization to induced arthritis (PCID).VNS stimulation started on day 13 and continued until day 20. The VNSstimulation inhibited the development of PCID.

FIG. 7 illustrates the effect of direct stimulation of the vagus nerve,showing attenuation of serum TNF concentrations. BALB/c mice receivedLPS (7.5 mg/kg, intraperitoneally) 5 minutes before either surgicaldissection alone or increasing intensities of electrical vagus nervestimulation. Blood was collected 2 hrs after endotoxin administration.Data are presented as mean±SEM (n=6-8 per group; **p<0.05).

FIG. 8 illustrates the anti-inflammatory and cardioinhibitory effects ofvagus nerve stimulation (VNS), showing that the two are dissociable.Electrocardiograms were recorded for 5 minutes from BALB/c micesubjected to neck dissection (sham surgery), vagus nerve dissection,transcutaneous vagus nerve stimulation (300 seconds, 2 Hz) or increasingintensities of electrical vagus nerve stimulation (1 V, 5 Hz, 2milliseconds; 5 V, 5 Hz, 2 milliseconds; 5 V, 30 Hz, 2 milliseconds).Changes in mean heart rate were compared with baseline. Data arepresented as mean±SEM (n=6-8 per group; **p<0.05).

FIG. 9A shows that the effective duration of action of vagus nervestimulation is between 48 and 72 hrs after VNS. BALB/c mice weresubjected to electrical vagus nerve stimulation (30 seconds, 1 V, 30 Hz,0.5 milliseconds) or neck dissection alone (control) on day 0 and wereallowed to recover for 2, 24, 48, or 72 hrs before LPS challenge (7.5mg/kg; intraperitoneally). Blood was collected 2 hrs after LPSadministration for tumor necrosis factor (TNF) analysis. Data arepresented as mean±SEM (n=6-8 per group; **p<0.05).

FIG. 9B illustrates the inhibition of TNF release from macrophages for48 to 72 hrs by acetylcholine. Primary human macrophages were treatedwith acetylcholine (10 μM) and pyridostigmine bromide (1 mM) for 1 hr,were transferred to fresh media, and then received 4 hrs of LPS (10ng/mL) stimulation beginning 2, 24, 48, or 72 hrs after acetylcholineexposure. Supernatants were collected and TNF was analyzed byenzyme-linked immunosorbent assay. Data are presented as mean±SEM of twoseparate experiments (**p<0.05).

FIG. 10A illustrates the beneficial effect of vagus nerve stimulation(VNS) on serum glucose concentrations in lethal endotoxemia. BALB/c micewere subjected to electrical vagus nerve stimulation (30 seconds, 1 V, 5Hz, 2 milliseconds) following lipopolysaccharide (LPS) administration(7.5 mg/kg, intraperitoneally). Animals were euthanized after 2 hrs.Data are presented as mean±SEM (n=5-8 per group; *p<0.05 vs. control;**p<0.05 vs. LPS).

FIG. 10B illustrates the effects of vagus nerve stimulation versusdexamethasone (DEX) on splenocyte viability. Mice were subjected toelectrical vagus nerve stimulation (30 seconds, 1 V, 5 Hz, 2milliseconds) or dexamethasone (25 mg/kg, intraperitoneally) 24 hrsbefore LPS administration (7.5 mg/kg, intraperitoneally). Animals wereeuthanized 2 hrs after LPS, spleens were harvested, and viablesplenocytes were measured. Data are presented as mean±SEM (n=6 pergroup; **p<0.05).

DETAILED DESCRIPTION OF THE INVENTION

Described herein are devices, systems, and method for decreasinginflammation by appropriate stimulation of one or more components of thecholinergic anti-inflammatory pathway, such as the vagus nerve. Inparticular, methods of stimulating the vagus nerve to decrease orsuppress the release of pro-inflammatory cytokines are described.

Direct (e.g. electrical or mechanical) stimulation of vagus nerve of asubject alleviates the symptoms of inflammatory disorders. As usedherein, a “subject” is preferably a mammal, more preferably a humanpatient but can also be a companion animal (e.g., dog or cat), a farmanimal (e.g., horse, cow, or sheep) or a laboratory animal (e.g., rat,mouse, or guinea pig). Preferable, the subject is human. As used herein,the term “vagus nerve” is used in its broadest sense, and may includeany nerves that branch off from the main vagus nerve, as well asganglions or postganglionic neurons that are connected to the vagusnerve. The vagus nerve is also known in the art as the parasympatheticnervous system and its branches, and the cholinergic nerve. The vagusnerve innervates principal organs including, the pharynx, the larynx,the esophagus, the heart, the lungs, the stomach, the pancreas, thespleen, the kidneys, the adrenal glands, the small and large intestine,the colon, and the liver. Stimulation can be accomplished by direct orindirect stimulation of the vagus nerve or an organ served by the vagusnerve.

In some variations, the stimulation is calibrated or controlled so thatit does not substantially affect any target or efferent except thoserelated to inflammation. For example, the stimulation provided to thevagus nerve may be below the threshold or frequency for affecting othervagus nerve-mediated effects, such as changes in heart rate, bloodpressure, etc.

As used herein, “direct stimulation” of the vagus nerve may meanactivating or stimulating the vagus nerve by non-pharmacological meanssuch as electrical, mechanical (e.g., massage or vibration), heat or UVirradiation. Activation can be accomplished by direct or indirectstimulation of the vagus nerve or an organ served by the vagus nerve.The vagus nerve innervates principal organs including, the pharynx, thelarynx, the esophagus, the heart, the lungs, the stomach, the pancreas,the spleen, the kidneys, the adrenal glands, the small and largeintestine, the colon, and the liver.

The disclosed methods include stimulating the any portion of thecholinergic anti-inflammatory pathway, including the vagus. For example,the entire vagus nerve (i.e., both the afferent and efferent nerves) maybe stimulated, or efferent nerve bundles may be isolated and thenstimulated directly. The latter method can be accomplished by separatingthe afferent from the efferent fibers in an area of the nerve where bothtypes of fibers are present. Alternatively, the efferent fibers arestimulated where no afferent fibers are present, for example close tothe target organ served by the efferent fibers. The efferent fibers canalso be activated by stimulating the target organ directly, e.g.,electrically, thus stimulating the efferent fibers that serve thatorgan. In other embodiments, the ganglion or postganglionic neurons ofthe vagus nerve can be stimulated. The vagus nerve can also be cut andthe distal end can be stimulated, thus only stimulating efferent vagusnerve fibers.

The cholinergic anti-inflammatory pathway (e.g., vagus nerve) can bestimulated by numerous methods including manually, mechanically,electrically or by electromagnetic radiation. Mechanical means of nervestimulation include, without limitation, stimulation by needle (e.g.,acupuncture). There is evidence that response to acupuncture may be atleast partially mediated by the vagus nerve. For example, it has beenshown that the response to electroacupuncture is attenuated aftervagotomy (Noguchi et al, Jpn. J. Physiol. 46(1): 53-58 (1996)).Mechanical stimulation may also include nerve stimulation usingultrasound as described, for example in Norton, BioMedical Engineering2(1): 6 (2003). Stimulation of the vagus nerve using heat orelectromagnetic radiation includes, without limitation, applying heat orinfrared, visible, ultraviolet, or other electromagnetic frequenciesfrom an energy source. The vagus nerve may also be stimulated bymagnetic stimulation; a description of magnetic nerve stimulation isprovided in Hsu et al, IEEE Trans Biomed Eng 50(11): 1276-85 (2003). Theentire teachings of these publications are incorporated herein byreference.

The site of stimulation of the cholinergic anti-inflammatory pathway(e.g., of the vagus nerve) may be in the cervical region (in the neck)and a region peripheral and distal of the cervical region including,supra-diaphragmatical or sub-diaphragmatical regions. Peripheral, distallocations include branches of the vagus nerve that innervate organs,including but not limited to, the spleen, the small intestine and thelarge intestine. The vagus nerve may also be stimulated endotracheallyor transesophageally. Endotracheal or transesophageal vagal nervestimulation may be accomplished using an endotracheal/esophageal nervestimulator (described, for example, in U.S. Pat. No. 6,735,471,incorporated herein by reference in its entirety). The vagus nerve canbe stimulated transesophageally using one or more esophageal electrodes(described, for example, in U.S. Pat. No. 5,571,150). The vagus nervecan also be stimulated using a transcutaneous nerve stimulator (asdescribed for example in U.S. Pat. No. 6,721,603, incorporated herein byreference in its entirety) or a percutaneous nerve stimulator. In oneembodiment, the vagus nerve is stimulated in the cervical region. Inanother embodiment, the vagus nerve is stimulated at a peripheral,distal location. In another embodiment, the vagus nerve is stimulated inthe brain by the device.

According to one embodiment, the vagus nerve is stimulated by deliveringan electrical signal generated by any suitable vagus nerve stimulators.For example, a commercial vagus nerve stimulator such as the CyberonicsNCP, or an electric probe can be used.

Examples of suitable vagus nerve stimulators are described, for example,in U.S. Pat. Nos. 4,702,254; 5,154,172; 5,231,988; 5,330,507; 6,473,644;6,721,603; 6,735,471; and U.S. Pat. App. Pub. 2004/0193231. Theteachings of all of these publications are incorporated herein byreference in their entirety.

The vagus nerve can be stimulated by means of either an implanted deviceor a device worn external to the patient's body, such as Cyberonics NCPdevice described in U.S. Pat. No. 5,231,988 or a Medtronic devicedescribed in U.S. Pat. No. 5,330,507. Both patents describe apparati forstimulating the right or left vagus nerve with continuous and/or phasicelectrical signal.

A schematic diagram of one variation of an electrical signal generatordevice suitable for practicing the methods described herein is shown inFIG. 1. Referring to FIG. 1, a typical signal generator 10 includes abattery (or set of batteries) 12, which may be of any typeconventionally employed for powering medical electronic devices. Battery12 is connected to a voltage regulator 14. Regulator 14 smoothes thebattery output to produce steady output voltage as well as providesvoltage multiplication or division if necessary.

Regulator 13 supplies power to signal controller 16. Signal controller16 can includes a microprocessor. Signal controller 16 controlsfunctions of the device such as output signal current or voltage, outputsignal frequency, output signal pulse width, output signal on-time,output signal off-time. Controller 16 can be programmed to control dailytimes for continuous or periodic modulation of vagal activity as well asoutput signal start delay time. Such programmability allows the outputsignal to be adjusted for the treatment regimen. The controller 16 mayalso limit the stimulation, so that it does not exceed a maximum levelfor intensity (e.g., voltage) or frequency (including on and/or offtime, etc.). In some variations, the controller controls the stimulationby regulating the output to the electrodes (via Driver 18) so that thesignal delivered to the tissue (e.g., vagus nerve) is within apredetermined range.

When device 10 is implanted, a built-in antenna (not shown) can be usedto enable communication between device 10 and external programming ormonitoring devices (not shown).

Signal controller 16 controls driver 18 which generates the desiredelectrical signal. The output signal is applied to the patient's bodyvia electrodes 20 a and 20 b.

Analyzer 22 can be provided to process any relevant physiologicalparameters of a patient such as heart rate or blood pressure detected bydetector 24.

As mentioned above, device 10 can be worn external to the patient's bodyor can be implanted. FIG. 2 illustrates one embodiment of an implantabledevice for practicing the methods described herein, where signalgenerator 10 is implanted in the patient's chest in a pocket formed bythe surgeon just below the skin. One suitable location for the generatoris in the patient's chest, as a pacemaker pulse generator would beimplanted, with the electrodes 20 a and 20 b implanted in the patient'sneck.

Electrodes 20 a and 20 b can be bipolar stimulating electrodes of thetype described in U.S. Pat. No. 4,573,481, incorporated herein byreference in its entirety. In this embodiment, electrodes form anassembly which is surgically implanted on the vagus nerve in thepatient's neck. The two electrodes are wrapped around the vagus nerve,and the assembly is secured to the nerve by a spiral anchoring tether asdisclosed in U.S. Pat. No. 4,979,511, incorporated herein by referencein its entirety.

Structurally, the electrode assembly can comprise two ribbons ofplatinum which are individually bonded to each of the two spiral loopswrapped around the vagus nerve. Each loop further includes siliconerubber. An additional helical loop that includes silicon rubber isprovided to tether the electrode assembly to the vagus nerve. The innerdiameter of the helical bipolar electrodes may typically be about twomillimeters (mm), and an individual spiral is about seven mm long(measured along the axis of the nerve).

Instead of implanting the electrode assembly in the patient's neck, theassembly may be implanted on the vagus nerve as it innervates any of theorgans listed above. The implantation of electrodes 20 a and 20 b isaccomplished in substantially the same manner as was described for theneck location.

The operation of signal generator 10 to control and treat inflammatorydisorders will be described by reference to the signal waveform andparameters shown in FIG. 3. The latter is an idealized representation ofthe output signal delivered by driver 18. FIG. 3 serves to clarifyterminology used to refer to the parameters of an electrical signal.Such parameters include signal on-time, signal off-time, signalfrequency, signal pulse width, signal current, and signal voltage.Treatment of inflammatory disorders can be accomplished by applyingvoltage to electrodes 20 a and 20 b as well as by driving a currentbetween electrodes 20 a and 20 b. While the pulses shown in FIG. 3 havepositive voltage or current output, electrical signals having negativeoutputs can also be used.

Signal controller 16 controls the output signal by limiting the outputto a suitable range of parameters specified above with reference to FIG.3. A range of each parameter can be chosen independently from any otherparameter. Alternatively, a combination of ranges for any number ofparameters can be chosen. Preferred examples of specific values for theparameters and combinations of parameters as provided below with respectto the controller are also applicable to the disclosed methods oftreatment.

Signal controller can limit signal voltage to a range from about 0.01Volt to about 1 Volt, preferably to a range from about 0.01 Volt toabout 0.1 Volt, more preferably, to a range from about 0.01 Volt toabout 0.05 Volt.

Signal controller can limit signal current to a range from about 1 mA toabout 100 mA, preferably to a range from about 1 mA to about 10 mA, morepreferably to a range from about 1 mA to about 5 mA.

In some embodiments, both signal voltage and signal current arecontrolled.

In other embodiments, either in addition to or independently fromcontrolling signal voltage, signal current or both, signal controllercan further control one or more parameters selected from pulse width,on-time and frequency. Signal controller can limit the pulse width to arange from about 0.1 ms to about 5 ms, preferably to a range from about0.1 ms to about 1 ms, more preferably to a range from about 0.1 ms toabout 0.5 ms. Signal controller can limit signal on-time from about 1second to about 120 seconds, preferably, to a range of from about10-seconds to about 60 seconds, more preferably, to a range from about20 seconds to about 40 seconds. Signal controller can limit signalfrequency to a range from about 0.1 Hz to about 30 Hz, preferably, to arange from about 1 Hz to about 30 Hz, more preferably, to a range fromabout 10 Hz to about 30 Hz.

In other embodiments, either in addition to or independently fromcontrolling signal voltage and/or signal current, as well as signalwidth, signal frequency and/or signal on-time, signal controller canfurther control signal off-time. In one embodiment, a subject can betreated with one pulse. In another embodiment, signal controller canlimit signal off-time to a range of over 5 minutes, preferably, over 2hours, more preferably, over 4 hours, even more preferably, over 8hours, still more preferably, over 12 hours. In another embodiment,signal controller can limit signal off-time to a range of from about 2hours to about 48 hours, preferably to a range from about 4 hours toabout 36 hours, more preferably, to a range from about 6 hours to about36 hours. In other preferred embodiments, signal controller can limitsignal off-time to a range selected from: from about 6 to about 36hours, from about 12 to about 36 hours, from about 16 to about 30 hoursand from about 20 to about 28 hours. Alternatively, signal off-time canbe undefined as one skilled in the art will readily determine thedesired time interval between two consecutive signals.

As mentioned above, various parameters can be limited to the specifiedranges alone or in combination. In one example, signal controller canlimit a combination of parameters as follows: signal voltage to a rangefrom about 0.01 Volt to about 1 Volt; pulse width to a range from about0.1 ms to about 5 ms; signal frequency to a range from about 0.1 Hz toabout 30 Hz; signal on-time from about 1 second to about 120 seconds.Signal off-time can be undefined. Alternatively, signal off-time can belimited to a range over about 5 minutes. In other preferred embodiments,signal controller can limit signal off-time to a range selected from:from about 6 to about 36 hours, from about 12 to about 36 hours, fromabout 16 to about 30 hours and from about 20 to about 28 hours.

In another example, signal controller can limit a combination ofparameters as follows: signal current to a range from about 1 mA toabout 100 mA; pulse width to a range from about 0.1 ms to about 5 ms;signal frequency to a range from about 0.1 Hz to about 30 Hz; signalon-time from about 1 second to about 120 seconds. Signal off-time can beundefined. Alternatively, signal off-time can be limited to a range overabout 5 minutes. In other preferred embodiments, signal controller canlimit signal off-time to a range selected from: from about 6 to about 36hours, from about 12 to about 36 hours, from about 16 to about 30 hoursand from about 20 to about 28 hours.

In a preferred embodiment, signal controller can limit a combination ofparameters as follows: signal voltage to a range from about 0.01 Volt toabout 0.1 Volt; pulse width to a range from about 0.1 ms to about 1 ms;signal frequency to a range from about 1 Hz to about 30 Hz; signalon-time to a range of from about 10 seconds to about 60 seconds; signaloff-time to a range of over 2 hours. Alternatively, signal off-time canbe undefined. In other preferred embodiments, signal controller canlimit signal off-time to a range selected from: from about 6 to about 36hours, from about 12 to about 36 hours, from about 16 to about 30 hoursand from about 20 to about 28 hours.

Alternatively, signal controller can limit a combination of parametersas follows: signal current to a range from about 1 mA to about 10 mA;pulse width to a range from about 0.1 ms to about 1 ms; signal frequencyto a range from about 1 Hz to about 30 Hz; signal on-time to a range offrom about 10 seconds to about 60 seconds; signal off-time to a range ofover 2 hours. Alternatively, signal off-time can be undefined. In otherpreferred embodiments, signal controller can limit signal off-time to arange selected from: from about 6 to about 36 hours, from about 12 toabout 36 hours, from about 16 to about 30 hours and from about 20 toabout 28 hours.

More preferably, signal controller can limit a combination of parametersas follows: signal voltage to a range from about 0.01 Volt to about 0.05Volt; pulse width to a range from about 0.1 ms to about 0.5 ms; signalto a range from about 10 Hz to about 30 Hz; signal on-time to a rangefrom about 20 seconds to about 40 seconds; signal off-time to a range offrom about 2 hours to about 24 hours. Alternatively, signal off-time canbe undefined. In other preferred embodiments, signal controller canlimit signal off-time to a range selected from: from about 6 to about 36hours, from about 12 to about 36 hours, from about 16 to about 30 hoursand from about 20 to about 28 hours. In other preferred embodiments,signal controller can limit signal off-time to a range selected from:from about 6 to about 36 hours, from about 12 to about 36 hours, fromabout 16 to about 30 hours and from about 20 to about 28 hours.

Alternatively, signal controller can limit a combination of parametersas follows: signal current to a range from about 1 mA to about 5 mA;pulse width to a range from about 0.1 ms to about 0.5 ms; signal to arange from about 10 Hz to about 30 Hz; signal on-time to a range fromabout 20 seconds to about 40 seconds; signal off-time to a range of fromabout 2 hours to about 24 hours. Alternatively, signal off-time can beundefined. In other preferred embodiments, signal controller can limitsignal off-time to a range selected from: from about 6 to about 36hours, from about 12 to about 36 hours, from about 16 to about 30 hoursand from about 20 to about 28 hours.

As used herein, “treatment” may include prophylactic and therapeutictreatment. “Prophylactic treatment” refers to treatment before onset ofan inflammatory condition to prevent, inhibit or reduce its occurrence.Therapeutic treatment is treatment of a subject who is alreadyexperiencing an inflammatory disorder.

“Inflammatory disorders” are usually mediated by an inflammatorycytokine cascade, defined herein as an in vivo release from cells of atleast one pro-inflammatory cytokine in a subject, wherein the cytokinerelease affects a physiological condition of the subject. Non-limitingexamples of cells that produce pro-inflammatory cytokines are monocytes,macrophages, neutrophils, epithelial cells, osteoblasts, fibroblasts,smooth muscle cells, and neurons.

As used herein, a “cytokine” is a soluble protein or peptide which isnaturally produced by mammalian cells and which act in vivo as humoralregulators at micro- to picomolar concentrations. Cytokines can, eitherunder normal or pathological conditions, modulate the functionalactivities of individual cells and tissues. A pro-inflammatory cytokineis a cytokine that is capable of causing any of the physiologicalreactions associated with inflammation, such as: vasodialation,hyperemia, increased permeability of vessels with associated edema,accumulation of granulocytes and mononuclear phagocytes, or depositionof fibrin. In some cases, the pro-inflammatory cytokine can also causeapoptosis, such as in chronic heart failure, where TNF has been shown tostimulate cardiomyocyte apoptosis. Non-limiting examples ofpro-inflammatory cytokines are tumor necrosis factor (TNF), interleukin(IL)-1.alpha., IL-1.beta., IL-6, IL-8, IL-18, interferon-γ, HMG-1,platelet-activating factor (PAF), and macrophage migration inhibitoryfactor (MIF). In one embodiments, the pro-inflammatory cytokine that isinhibited by cholinergic agonist treatment is TNF, an IL-1, IL-6 orIL-18, because these cytokines are produced by macrophages and mediatedeleterious conditions for many important disorders, for exampleendotoxic shock, asthma, rheumatoid arthritis, inflammatory biledisease, heart failure, and allograft rejection. In most preferredembodiments, the pro-inflammatory cytokine is TNF.

Pro-inflammatory cytokines are to be distinguished fromanti-inflammatory cytokines, such as IL-4, IL-10, and IL-13. Inpreferred embodiments, release of anti-inflammatory cytokines is notinhibited by cholinergic agonists.

When referring to the effect of the vagus nerve stimulation on aninflammatory disorder, the use of the terms “treatment”, “inhibition”,“decrease” or “attenuation” encompasses at least a small but measurablereduction in the symptoms associated with the disorder being treated.

“Treatment” includes both therapeutic and prophylactic treatments.

Described herein are methods of treatment of inflammatory disorders orconditions mediated by an inflammatory cytokine cascade. In one aspect,the disorder is not ileus, asthma or cystic fibrosis.

In another embodiment, the methods described herein may be methods oftreating ileus. As used herein, “ileus” means a short term cessation(less than one month, typically, less than 2 weeks, often less than 1week) of function of bowels not caused by chronic condition such asgastric ulcer, gastroesophageal reflux, diabetic gastroparesis,postvagotomy, and postgastrectomy. In one embodiment ileus ischaracterized by inflammation of intestinal smooth muscles.

The methods describe herein can be used to treat ileus caused bymanipulation of the bowels during abdominal surgery (“post-operativeileus”), or administration of narcotics or chemotherapeutic agents suchas during cancer chemotherapy. Successful treatment of ileus includesreduction and alleviation of symptoms of ileus. The terms “reduction” or“alleviation”, when referring to symptoms of ileus in a subject,encompass reduction in measurable indicia over non-treated controls.Such measurable indicia include, but are not limited to retention timeof gastric content after gavage and myeloperoxidase activity (units pergram) in the gastrointestinal musculature. In preferred embodiments, themeasurable indicia are reduced by at least 20% over non-treatedcontrols; in more preferred embodiments, the reduction is at least 70%;and in still more preferred embodiments, the reduction is at least 80%.In a most preferred embodiment, the symptoms of ileus are substantiallyeliminated.

In one embodiment, the ileus to be treated is a post-operative ileus,i.e. ileus that occurs after abdominal surgery.

With respect to ileus, “treatment” includes pre-operative,peri-operative and post-operative treatment of ileus. Thus, “treatment”means prophylactic treatment of subjects at risk for ileus, for example,a subject undergoing abdominal surgery, experiencing abdominal surgery,or being administered narcotics or chemotherapeutic agents. With respectto ileus, “prophylactic treatment” refers to treatment before onset ofileus to prevent, inhibit or reduce the occurrence of ileus. Forexample, a subject at risk for ileus, such as a subject undergoingabdominal surgery, or about to undergo abdominal surgery, or being (orabout to be) administered narcotics or chemotherapeutic agents can beprophylactically treated according to the method described herein priorto the anticipated onset of ileus. For example, a subject about toundergo surgery can be treated up to eight days before surgery, up toseven days before surgery, up to six days before surgery, up to fivedays before surgery, up to four days before surgery, up to three daysbefore surgery, 48 hours prior to surgery, up to 36 hours prior tosurgery, up to 24 hours prior to surgery, up to 12 hours prior tosurgery, up to 6 hours before surgery, up to 3 hours before surgery, upto 2 hours before surgery, up to one hour before surgery and up to theonset of surgery. In another example, a subject can be treated duringthe surgery or administration of narcotics or chemotherapeutic agents.In another embodiment, the subject can be treated after the completionof surgery of administration of narcotics or chemotherapeutic agents.For example, a subject can be treated immediately after surgery, up toone hour after surgery, up to 2 hours after surgery, up to 3 hours aftersurgery, up to 6 hours after surgery, up to 12 hours after, up to 24hours after, up to 36 hours after, up to 48 hours after surgery, up tothree days after surgery, up to four days after surgery, up to five daysafter surgery, up to six days after surgery, up to seven days aftersurgery or up to eight days after surgery. “Treatment” of ileus alsoincludes therapeutic treatment, where the subject is alreadyexperiencing ileus.

In one example, the subject can be treated pre-operatively,post-operatively, or peri-operatively once, twice, three times, fourtimes or more than four times during the intervals described above.Alternatively, the subject can be treated by any combination ofpre-operative, post-operative or peri-operative regimens during theintervals described above.

Preferably, ileus is treated by stimulating the vagus nerveendotracheally or transesophageally. Any device capable of performingthis function can be employed. An example of an endotracheal/esophagealnerve stimulator is described in U.S. Pat. No. 6,735,471, incorporatedherein by reference in its entirety.

Also described herein is the use of any of the devices described abovein the manufacture of a therapeutic article for treating inflammatorydisorders in a subject, wherein the device, in operation, directly orindirectly stimulates the vagus nerve to treat inflammatory disorders.The term “in operation” is intended to mean the device during use orapplication of the device on, to, or near the subject to directlystimulate the vagus nerve to treat inflammatory disorders.

In a further aspect, the methods described relate to the use of a devicein the manufacture of a therapeutic article for treating inflammatorydisorders in a subject, wherein the device is used solely to stimulatethe vagus nerve for the purpose of treating inflammatory disorders. Theterm “solely” includes the use of the device to selectively treatinflammatory disorders where other diseases or conditions couldpotentially be treated by stimulation of the vagus nerve.

In some variations, only inflammatory disorders are treated or affectedby the direct stimulation of the vagus nerve by the device. In oneembodiment, the device may be adapted specifically to treat onlyinflammatory disorders by direct stimulation of the vagus nerve.

The condition can be one where the inflammatory cytokine cascade causesa systemic reaction, such as with septic shock. Alternatively, thecondition can be mediated by a localized inflammatory cytokine cascade,as in rheumatoid arthritis.

Non-limiting examples of conditions which can be usefully treated usingthese methods include ileus, appendicitis, peptic ulcer, gastric ulcer,duodenal ulcer, peritonitis, pancreatitis, ulcerative colitis,pseudomembranous colitis, acute colitis, ischemic colitis,diverticulitis, epiglottitis, achalasia, cholangitis, cholecystitis,hepatitis, Crohn's disease, enteritis, Whipple's disease, allergy,anaphylactic shock, immune complex disease, organ ischemia, reperfusioninjury, organ necrosis, hay fever, sepsis, septicemia, endotoxic shock,cachexia, hyperpyrexia, eosinophilic granuloma, granulomatosis,sarcoidosis, septic abortion, epididymitis, vaginitis, prostatitis,urethritis, bronchitis, emphysema, rhinitis, pneumonitis,pneumotransmicroscopicsilicovolcanoconiosis, alvealitis, bronchiolitis,pharyngitis, pleurisy, sinusitis, influenza, respiratory syncytial virusinfection, HIV infection, hepatitis B virus infection, hepatitis C virusinfection, herpes virus infection disseminated bacteremia, Dengue fever,candidiasis, malaria, filariasis, amebiasis, hydatid cysts, burns,dermatitis, dermatomyositis, sunburn, urticaria, warts, wheals,vasulitis, angiitis, endocarditis, arteritis, atherosclerosis,thrombophlebitis, pericarditis, myocarditis, myocardial ischemia,periarteritis nodosa, rheumatic fever, Alzheimer's disease, coeliacdisease, congestive heart failure, adult respiratory distress syndrome,meningitis, encephalitis, multiple sclerosis, cerebral infarction,cerebral embolism, Guillame-Barre syndrome, neuritis, neuralgia, spinalcord injury, paralysis, uveitis, arthritides, arthralgias,osteomyelitis, fasciitis, Paget's disease, gout, periodontal disease,rheumatoid arthritis, synovitis, myasthenia gravis, thyroiditis,systemic lupus erythematosis, Goodpasture's syndrome, Behcet's syndrome,allograft rejection, graft-versus-host disease, Type I diabetes,ankylosing spondylitis, Berger's disease, Reiter's syndrome andHodgkin's disease.

In another embodiment, the examples of conditions which can be usefullytreated include appendicitis, peptic ulcer, gastric ulcer, duodenalulcer, peritonitis, pancreatitis, ulcerative colitis, pseudomembranouscolitis, acute colitis, ischemic colitis, diverticulitis, epiglottitis,achalasia, cholangitis, cholecystitis, hepatitis, Crohn's disease,enteritis, Whipple's disease, allergy, anaphylactic shock, immunecomplex disease, organ ischemia, reperfusion injury, organ necrosis, hayfever, sepsis, septicemia, endotoxic shock, cachexia, hyperpyrexia,eosinophilic granuloma, granulomatosis, sarcoidosis, septic abortion,epididymitis, vaginitis, prostatitis, urethritis, bronchitis, emphysema,rhinitis, pneumonitis, pneumotransmicroscopicsilicovolcanoconiosis,alvealitis, bronchiolitis, pharyngitis, pleurisy, sinusitis, influenza,respiratory syncytial virus infection, HIV infection, hepatitis B virusinfection, hepatitis C virus infection, herpes virus infectiondisseminated bacteremia, Dengue fever, candidiasis, malaria, filariasis,amebiasis, hydatid cysts, burns, dermatitis, dermatomyositis, sunburn,urticaria, warts, wheals, vasulitis, angiitis, endocarditis, arteritis,atherosclerosis, thrombophlebitis, pericarditis, myocarditis, myocardialischemia, periarteritis nodosa, rheumatic fever, Alzheimer's disease,coeliac disease, congestive heart failure, adult respiratory distresssyndrome, meningitis, encephalitis, multiple sclerosis, cerebralinfarction, cerebral embolism, Guillame-Barre syndrome, neuritis,neuralgia, spinal cord injury, paralysis, uveitis, arthritides,arthralgias, osteomyelitis, fasciitis, Paget's disease, gout,periodontal disease, rheumatoid arthritis, synovitis, myasthenia gravis,thyroiditis, systemic lupus erythematosis, Goodpasture's syndrome,Behcet's syndrome, allograft rejection, graft-versus-host disease, TypeI diabetes, ankylosing spondylitis, Berger's disease, Reiter's syndromeand Hodgkin's disease.

In more preferred embodiments, the condition is ileus, appendicitis,peptic, gastric or duodenal ulcers, peritonitis, pancreatitis,ulcerative, pseudomembranous, acute or ischemic colitis, hepatitis,Crohn's disease, asthma, allergy, anaphylactic shock, organ ischemia,reperfusion injury, organ necrosis, hay fever, sepsis, septicemia,endotoxic shock, cachexia, septic abortion, disseminated bacteremia,burns, Alzheimer's disease, coeliac disease, congestive heart failure,adult respiratory distress syndrome, cerebral infarction, cerebralembolism, spinal cord injury, paralysis, allograft rejection orgraft-versus-host disease. In more preferred embodiments, the conditionis endotoxic shock.

In another embodiment, the condition is appendicitis, peptic, gastric orduodenal ulcers, peritonitis, pancreatitis, ulcerative,pseudomembranous, acute or ischemic colitis, hepatitis, Crohn's disease,asthma, allergy, anaphylactic shock, organ ischemia, reperfusion injury,organ necrosis, hay fever, sepsis, septicemia, endotoxic shock,cachexia, septic abortion, disseminated bacteremia, burns, Alzheimer'sdisease, coeliac disease, congestive heart failure, adult respiratorydistress syndrome, cerebral infarction, cerebral embolism, spinal cordinjury, paralysis, allograft rejection or graft-versus-host disease.

In another preferred embodiment, the conditions are ileus, sepsis,endotoxic shock, allograft rejection, rheumatoid arthritis, adultrespiratory distress syndrome, asthma, systemic lupus erythematosis,pancreatitis, peritonitis, burns, myocardial ischemia, allograftrejection, graft-versus-host disease, congestive heart failure, organischemia, reperfusion injury, cachexia and cystic fibrosis.

In another embodiment, the conditions are sepsis, endotoxic shock,allograft rejection, rheumatoid arthritis, adult respiratory distresssyndrome, asthma, systemic lupus erythematosis, pancreatitis,peritonitis, burns, myocardial ischemia, allograft rejection,graft-versus-host disease, congestive heart failure, organ ischemia,reperfusion injury, cachexia and cystic fibrosis.

In another preferred embodiment, the conditions are ileus, appendicitis,ulcerative colitis, Crohn's disease, allergy, reperfusion injury,systemic lupus erythematosus, hepatitis, Behcet's syndrome, multiplesclerosis and atherosclerosis.

In another embodiment, the conditions are appendicitis, ulcerativecolitis, Crohn's disease, allergy, reperfusion injury, systemic lupuserythematosus, hepatitis, Behcet's syndrome, multiple sclerosis andatherosclerosis.

In another embodiment, the conditions are ileus, endotoxic shock andsepsis. In another embodiment, the conditions are endotoxic shock andsepsis.

Also described herein is the use of an electrical signal generator forconstruction of a medical device for treating a subject suffering from,or at risk for ileus. In yet another embodiment, an electrical signalgenerator may be used for construction of a medical device for treatinga subject suffering from, or at risk for post-operative ileus. Thedevice comprises an electrode assembly for delivering an electricalsignal to the vagus nerve of the subject; and a controller controllingthe electrical signal by limiting the signal voltage to a range from0.01 Volt to 1 Volt. Preferably, the controller is limiting the signalvoltage to a range from 0.01 Volt to 0.05 Volt. In another embodiment,the controller is limiting pulse width to a range from 0.1 ms to 5 ms;signal frequency to a range from 0.1 Hz to 30 Hz; and signal on-time toa range from 1 second to 120 seconds. In yet another embodiment, thecontroller is limiting signal voltage to a range from 0.01 Volt to 0.05Volt; pulse width to a range from 0.1 ms to 0.5 ms; signal frequency toa range from 10 Hz to 30 Hz; and signal on-time to a range from 20seconds to 40 seconds.

In another embodiment, an electrical signal generator may be used forconstruction of a medical device for treating a subject suffering from,or at risk for ileus. The device comprises an electrode assembly fordelivering an electrical signal to the vagus nerve of the subject; and acontroller controlling the electrical signal by limiting the signalvoltage to a range from 0.01 Volt to 1 Volt, pulse width to a range from0.1 ms to 5 ms; signal frequency to a range from 0.1 Hz to 30 Hz; signalon-time to a range from 1 second to 120 seconds; and signal off-time toa range over 2 hours.

Preferably, the controller limits the signal off-time to a range from 2hours to 48 hours, and more preferably to a range of 16 hours to 30hours. In another embodiment, the device, in operation, directlystimulates the vagus nerve to treat ileus. In another embodiment, thedevice is used solely to stimulate the vagus nerve for the purpose oftreating ileus.

The methods and systems described above are illustrated by the followingexamples which are not intended to be limiting in any way.

EXEMPLIFICATION Example 1 Electrical Vagus Nerve Stimulation UsingDecreased Stimulation Intensities and Durations are Sufficient forActivation of the Cholinergic Anti-Inflammatory Pathway

To determine whether decreased stimulation parameters could achieveanti-inflammatory effects, intact vagus nerves were electricallystimulated at progressively lower stimulation intensities and durationsin the setting of lethal endotoxemia. Male 8- to 12-week-old BALB/c mice(25-30 g; Taconic) were housed at 25° C. on a 12 hour light/dark cycle.Animals were allowed to acclimate to the facility for at least 7 daysprior to experimental manipulation. Standard mouse chow and water werefreely available. All animal experiments were performed in accordancewith the National Institutes of Health (NIH) Guidelines under protocolsapproved by the Institutional Animal Care and Use Committee of the NorthShore-Long Island Jewish Research Institute.

Mice were anesthetized with isoflurane (1.5-2.0%) and placed supine onthe operating table. A ventral cervical midline incision was used toexpose and isolate the left cervical vagus nerve. For electricalstimulation, the intact vagus nerve was placed across bipolar platinumelectrodes (Plastics One) connected to a stimulation module (STM100C,Biopac Systems) and controlled by an acquisition system (MP150, BiopacSystems). Electrical stimulation parameters were programmed usingAcqKnowledge software (Biopac Systems). Stimulation parameters included(100 mA, 2 ms, 5 Hz) for 20 min (10 min before LPS administration and 10min after), (100 mA, 2 ms, 5 Hz) for 2 min (1 min before LPSadministration and 1 min after), (100 mA, 2 ms, 5 Hz) for 30 sec (5 minafter LPS administration), and (1 mA, 0.5 ms, 30 Hz) for 30 sec (5 minafter LPS administration). Sham operated electrical VNS mice underwentcervical incision followed by dissection of the underlying submandibularsalivary glands only. The vagus nerve was neither exposed nor isolated.

Mice were injected with endotoxin (Escherichia coli LPS 0111:B4; Sigma)that was dissolved in sterile, pyrogen-free saline at stockconcentrations of 1 mg/ml. LPS solutions were sonicated for 30 minimmediately before use for each experiment. Mice received an LD.sub.50dose of LPS (7.5 mg/kg, i.p.). Blood was collected 2 h after LPSadministration, allowed to clot for 2 h at room temperature, and thencentrifuged for 15 min at 2,000.times.g. Serum samples were stored at−20.degree.C. before analysis. TNF concentrations in mouse serum weremeasured by ELISA (R & D Systems).

As shown in FIG. 5, all four stimulation parameters were sufficient forTNF suppression. The control mice group who received LPS followed bysham VNS had a mean serum TNF level of 2755.+−.424 pg/ml. Serum TNFlevels in the electrical VNS groups were as follows; 20 min (712.+−.128pg/ml, 25.8% of control, p=0.02), 2 min (688.+−.114 pg/ml, 25.0% ofcontrol, p=0.02), 30 sec at 100 mA (821.+−.378 pg/ml, 29.8% of control,p=0.46), and 30 sec at 1 mA (767.+−.144 pg/ml, 27.8% of control,p=0.03). The 30 sec 1 mA group corresponds to a clinically approvedstimulation protocol (REF).

These results indicate that cholinergic anti-inflammatory pathwayactivation is responsive to physiologic, clinically well-toleratedelectrical stimulation parameters. Additionally, the application ofsupraphysiologic current doses or prolonged stimulation durations doesnot provide any additional benefits in terms of reduced pro-inflammatorycytokine production.

Example 2 The Effective Duration of Action of Electrical Vagus NerveStimulation-Mediated TNF Suppression is Between Two and Three Days

To determine how long the anti-inflammatory effects of vagus nervestimulation last after the completion of stimulation, mice underwentelectrical stimulation for 30 sec (1 mA, 0.5 ms, 30 Hz), and wereallowed to recover for defined time periods prior to LPS administration.Control mice underwent sham surgery at time 0 and were challenged withLPS at the identical time periods as stimulated mice. Results for thefour experimental groups are depicted in FIG. 5. Waiting for two hoursbetween VNS and subsequent lipopolysaccharide (LPS) administrationresulted in a 71% suppression of TNF (control=1606.+−.326 pg/ml vs.VNS=474.+−.157 pg/ml, p=0.01). Waiting for one day between VNS and LPSadministration resulted in a 72% suppression of TNF (control=2813.+−.503pg/ml vs. VNS=783.+−.87 pg/ml, p=0.004). Waiting two days between VNSand LPS resulted in a 44% suppression of TNF (control=1590.+−.351 pg/mlvs. VNS=892.+−.85 pg/ml, p=0.09). Finally, waiting for three daysresulted in no TNF suppression (control=1253.+−.202 pg/ml vs.VNS=1393.+−.263 pg/ml, p=0.7). Animals were euthanized two hours afterLPS administration.

These results indicate that the cholinergic anti-inflammatory pathway'seffects are very long lasting, persisting for at least two days afterstimulation. Furthermore, there was no significant difference in theanti-inflammatory effects between the two hour delay as opposed to a oneday delay prior to LPS challenge. Finally, the data indicate that theanti-inflammatory effects of vagus nerve stimulation in this model haddissipated by three days after stimulation.

Example 3 Electrical Vagus Nerve Stimulation Improves Severity ofArthritis in a Rat Model of Collagen-Induced Arthritis

To determine if vagus nerve stimulation could delay the onset orameliorate the severity of arthritis in a rat collagen-induced arthritismodel, rats received repeated vagus nerve stimulation via implantedelectrodes for several days after collagen immunization and were scoredfor arthritis severity.

Purified Rat Type II Collagen (CII) (Chondrex, Redmond, Wash., USA) wasdissolved in 0.01M acetic acid. Equal volumes of collagen solution andincomplete Freund's adjuvant (IFA; Difco Laboratories, Detroit, Mich.)were emulsified at 4.degree.C. so that 200 ul of emulsion contains 150ug of rat CII (Akerlund et al, Clinical & Experimental Immunology 1999115: 32-41; Kokkola R et al., Arthritis Rheum. 2003 48:2052-8). Ratswere immunized intradermally at the base of the tail with a volume of200 ul per animal. A chronic, destructive arthritis developed with amean onset of 14 days after immunization.

A previously described, arthritis clinical scoring system was utilized(Kokkola R et al., Arthritis Rheum 2003. 48(7): 2052-2058). This scoringsystem has proven reliable and highly discriminative for therapeuticstudies (Akerlund et al, Clin Exp Immunol 1999, 115:32-41). Rats wereobserved daily for clinical signs of arthritis, including erythema andswelling of the joints. The interphalangeal joints of the digits, themetacarpophalangeal joint and wrist in the forepaw, and themetatarsophalangeal joint and ankle joint in the hind paw are eachconsidered as one category of joint. Each paw was scored on a scale of0-4 as follows: 0=unaffected, 1=1 type of joint affected, 2=2 types ofjoints affected, 3=3 types of joints affected, 4=3 types of jointsaffected and maximal erythema and swelling. An arthritis index wascalculated for each rat and expressed as the cumulative score for allpaws, with a maximum possible score of 16. Two independent observersperformed all arthritis evaluations. The observers were additionallyblinded to the identity of the animals.

Electrical vagus nerve stimulation was started on the 13th day postcollagen immunization day (PCID). VNS rats were stimulated for 10 minonce a day (5 V, 1-2 mA; 0.5-millisecond pulse; 30 Hz; 10 min on-time ofalternating 30 seconds “on” and 300 seconds “off”) through day 20 (day16 was skipped). These stimuli were generated using the STMISOCstimulation adapter, STM100C stimulator module, and MP150 DataAcquisition System, all from Biopac Systems, Inc. Where indicated, allanimals were anesthetized using isoflurane inhalation gas (2-4%). Duringsurgical procedures, animals were placed on a maintenance anesthesiadose via a mask delivery system. Following isoflurane anesthesiainduction, animal were placed in supine position, and a 2 cm ventralmidline cervical incision was made between the mandible and sternum. Thesubcutaneous tissue was dissected and retracted laterally. The mandiblesalivary glands were bluntly separated and retracted laterally. The leftvagus nerve was isolated between the sternomastoid and sternohyoidmuscles, dissected free from the neighboring carotid artery, andcontrolled with a 4-0 silk suture. A Teflon-coated silver electrode0.003 inch in diameter was secured to the vagus nerve by multiple 360degree circular wrappings around the nerve. The Teflon only was strippedfrom the ends of the wire to minimize electrical stimulation of thesurrounding cervical muscles. The silver wire ends then were tunneledsubcutaneously around the left neck to the dorsal cervical midline. Atthis point, they were exited through the skin and be attached tostimulating wires traveling through the tether apparatus.

As shown in FIG. 6, repeated electrical stimulation of the vagus nerveresulted in decreased clinical signs of arthritis (as measured byerythema and swelling of the joints) as compared with control and shamanimals (stimulated rats: N=4; sham: N=5; control: N=3.) On day 16, thearthritis score in rats receiving vagus nerve stimulation wassignificantly less than that in control and sham animals (p<0.05). Onday 19, the arthritis score in rats receiving vagus nerve stimulationwas significantly less than that in sham treated animals (p<0.05). Theseresults indicate that repeated vagus nerve stimulation is effective atlessening arthritis severity in collagen-induced arthritis.

Example 4 Mouse Model for Electrical Stimulation with Endotoxemia

Animals. Male 8- to 12-wk-old BALB/c mice (25-30 g; Taconic) were housedin groups at 25° C. on a 12-hr light/dark cycle. Animals were acclimatedto our facility for 7 or more days. All animal experiments wereperformed in accordance with the National Institutes of HealthGuidelines under protocols approved by the Institutional Animal Care andUse Committee of the Feinstein Institute for Medical Research. Animalsreceived different treatments as described subsequently. The allocationof animals to the different treatment groups (five to eight animals pergroup) was performed randomly. The different number of animals perexperimental groups is a result of multiple experiments or deaths thatoccurred before experimental end points.

Endotoxemia. Mice were injected intraperitoneally withlipopolysaccharide (LPS; Escherichia coli 0111:B4; Sigma) dissolved insterile, pyrogen-free saline that was sonicated for 30 mins immediatelybefore use. Two hours after injection, blood was collected, allowed toclot for 2 hrs at room temperature, and then centrifuged at roomtemperature for 15 mins at 2000×g. Serum samples were stored at −20° C.before analysis. Enzyme-linked immunosorbent assay was used to measuretumor necrosis factor (TNF) concentrations according to themanufacturer's instructions (R&D Systems, Minneapolis, Minn.).

Electrical Vagus Nerve Stimulation. Mice were anesthetized by isoflurane(1.5% to 2.5%) using a cone mask. A midline cervical incision was madeto expose the left vagus, which was suspended across bipolar platinumelectrodes (Plastics One) connected to a stimulation module (STM100C,Biopac Systems) and controlled by an acquisition system (MP150, BiopacSystems). Electrical stimulation variables were programmed usingAcqKnowledge software (Biopac Systems) and included 1 V, 2 milliseconds,5 Hz for 20 mins (10 mins before LPS and 10 mins after); 1 V, 2milliseconds, 5 Hz for 2 mins (1 min before LPS and 1 min after); 1 V, 2milliseconds, 5 Hz for 30 seconds (5 mins after LPS); and 1 V, 0.5milliseconds, 30 Hz for 30 seconds (5 mins after LPS). Sham-operatedmice underwent subcutaneous tissue dissection without exposure of thevagus nerve.

Subdiaphragmatic Vagotomy. A midline laparotomy incision was made, andthe intestines and stomach were retracted to expose the distalesophagus. The ventral vagal branch was identified and divided usingsharp dissection. The esophagus was encircled and rotated to expose anddivide the dorsal vagal branch. The incision was closed using 6-0polypropylene sutures. Animals received 1 mL of 0.9% normal salinesubcutaneously after surgery. Mice recovered for 7 days before furtherexperimentation.

Heart Rate Measurement. Two unipolar electrodes were placed onto theanterior chest wall of anesthetized mice and attached to an amplifier(ECG100C) and processing unit (MP150). The electrocardiogram wasprocessed offline using AcqKnowledge software. Baselineelectrocardiograms were recorded for 5 mins. Experimental groupsincluded neck dissection (sham surgery), vagus nerve dissection,transcutaneous vagus nerve stimulation, or escalating doses ofelectrical vagus nerve stimulation (1 V, 5 Hz, 2 milliseconds; 5 V, 5Hz, 2 milliseconds; 5 V, 30 Hz, 0.5 milliseconds). Electrocardiogramswere recorded and mean heart rates were compared with baseline values.

Generation of primary Human Macrophages. Peripheral blood mononuclearcells were isolated from the blood of normal volunteers (Long IslandBlood Services, Melville, N.Y.) over a Ficoll-Hypaque (PharmaciaBiotech, Uppsala, Sweden) density gradient. Monocytes were isolated byadherence. Macrophages were generated with 2 ng/mL human MCSF for 5 daysin RPMI 1640 medium (Life Technologies, Grand Island, N.Y.) supplementedwith 10% human serum, penicillin (100 units/mL, Life Technologies),streptomycin (100 μg/mL, Life Technologies), and glutamine (2 mM, LifeTechnologies). To determine the effect of acetylcholine on endotoxinresponse, the cells were treated with acetylcholine chloride (10 μM,Sigma) in the presence of acetylcholine esterase inhibitor(pyridostigmine bromide, 1 mM) in Opti-MEM I media (GibcoBRL) for 1 hr.The cells were washed once with 1× phosphate buffered saline (Fisher)and suspended in complete medium supplemented with human MCSF. Themacrophages received 4 hrs of LPS (10 ng/mL, E. coli 0111:B4, Sigma)stimulation in Opti-MEM I, beginning 2, 24, 48, and 72 hrs afteracetylcholine exposure. Supernatants were collected and TNF was analyzedby enzyme-linked immunosorbent assay.

Cecal Ligation and Puncture. CLP was performed on BALB/c mice asdescribed previously (19). Animals received antibiotic (Primaxin; 0.5mg/kg, subcutaneously) and 0.9% normal saline (20 mL/kg body weight,subcutaneously) immediately after surgery. Mice underwent transcutaneousvagus nerve stimulation or sham stimulation beginning 24 hrs aftersurgery and thereafter twice a day for 2 days. Serum HMGB1 levels weredetermined 44 hrs after surgery by Western blot as described previously(14, 17). HMGB1 concentrations were calculated against standard curvesgenerated using purified recombinant HMGB1 (14, 17). Seruminterleukin-10 levels were measured using Cytometric Bead Array (BectonDickinson) according to the manufacturer's instructions.

Clinical Sickness Score. Animals were assessed 44 hrs after CLP. Thesickness score is composed of four clinical signs, including diarrhea,piloerection, spontaneous eye opening, and activity level. The presenceof each component is worth either 1 point (diarrhea, piloerection) or1-2 points (eye opening, activity level), depending on severity. Amaximum score of 6 denotes a moribund animal with 100% mortality within24 hrs. A score of 0 denotes a healthy, nonseptic animal.

Statistics. All data are expressed as mean±SEM. One-way analysis ofvariance followed by the Bonferroni correction was used to compare meanvalues between three groups. The two-tailed Student's t-test was used tocompare mean values between two groups. Differences in survival weredetermined using the log-rank test. P values<0.05 were consideredsignificant.

Results

Electrical stimulation was chronically administered to mice usingimplanted wire electrodes. Increasing doses of electricity followingsurgical isolation of the vagus nerve did not suppress TNFconcentrations further, as illustrated in FIG. 7.

Anti-Inflammatory and Cardioinhibitory Effects of Vagus NerveStimulation are Dissociable.

The vagus nerve modulates numerous autonomic functions (20). To addressthe specificity of vagal anti-inflammatory signaling, we measured heartrate in animals receiving vagus nerve dissection, transcutaneous vagusnerve stimulation, or electrical vagus nerve stimulation (1 V, 5 Hz, 2milliseconds) and observed no significant effects on heart rate with anyof these treatments, as shown in FIG. 8. To ensure that vagus nervestimulation can elicit “classic” cardioinhibitory effects, we deliveredmore intense stimuli (5 V, 5 Hz, 2 milliseconds; or 5 V, 30 Hz, 2milliseconds) and observed a 27.3%±2.3% and 49.1% 2.1% decrease in heartrate, respectively (p<0.05).

Effective Duration of Action of Vagus Nerve Stimulation and CholinergicAgonists is Between 48 and 72 hrs.

To study the effective duration of action of vagal anti-inflammatorysignaling, we gave the mice electrical vagus nerve stimulation or shamstimulation, followed by defined recovery periods before endotoxinchallenge. We observed that vagus nerve stimulation significantlyreduced serum TNF concentrations when LPS was administered 48 hrsfollowing treatment, but not after 72 hrs. This is illustrated in FIG.9A.

To elucidate a mechanism for this relatively long neural duration ofaction of the anti-inflammatory effect of vagus nerve stimulation, wenext examined the TNF-suppressive effects of cholinergic agonists onendotoxin-stimulated primary human macrophages. Macrophage cell cultureswere stimulated with acetylcholine together with theacetylcholinesterase inhibitor pyridostigmine for 1 hr, and then cellswere washed and suspended in fresh media. Macrophages were stimulatedwith endotoxin 24, 48, or 72 hrs postexposure to cholinergic treatment.We observed that cholinergic treatment significantly attenuated TNFrelease for 48 hrs, but not 72 hrs after exposure, as shown in FIG. 9B.These results suggest that cholinergic signaling in macrophages maycontribute to the long-lived anti-inflammatory effects of vagus nervestimulation. For example, refer to FIG. 9A.

Vagus Nerve Stimulation Fails to Induce Hyperglycemia or Cell Death.

The systemic side effect profile of vagus nerve stimulation is currentlyunknown. We compared vagus nerve stimulation to administration ofglucocorticoids, a previously known approach in the treatment ofinflammatory diseases, by measuring serum glucose concentrations andsplenocyte viability in endotoxemic mice, as shown in FIG. 10A. Weobserved that vagus nerve stimulation significantly lowered serumglucose concentrations during lethal endotoxemia. Administration ofdexamethasone significantly reduced viable splenocyte counts, whilevagus nerve stimulation preserved splenocyte viability, as illustratedin FIG. 10B.

As discussed above, the nervous system regulates pro-inflammatorycytokine production through an α7nAChR-dependent, vagus nerve mediatedpathway to the spleen. Electrical vagus nerve stimulation inhibitspro-inflammatory cytokine production and prevents lethal shock in acutemodels of systemic inflammation.

HMGB1 is a necessary and sufficient mediator of lethal organ damage inmurine CLP sepsis. Systemic HMGB1 concentrations are significantlyelevated in this model, while neutralizing antibodies directed againstHMGB1 significantly reduce organ damage and improve survival.Pharmacologic agents that reduce circulating HMGB1 concentrations, suchas ethyl pyruvate and nicotine, also provide significant protectionagainst polymicrobial sepsis lethality. In addition, infusion of HMGB1to rodents causes organ damage and epithelial barrier failure. On thecontrary, the pluripotent, pro-inflammatory cytokine TNF has not beenfound to be a critical mediator of organ damage and lethality in thismodel. Vagus nerve stimulation significantly reduces systemic HMGB1concentrations in septic mice and thereby protects against thedevelopment of lethal organ damage.

Pharmacologic α7nAChR agonists, such as nicotine, can mimic the effectsof vagus nerve stimulation but may be complicated by poor specificityand systemic toxicity. We show here that vagal anti-inflammatorysignaling is specific and dissociable from heart rate regulation,suggesting that it may be a less toxic route for activating thecholinergic anti-inflammatory pathway. Interestingly, the vagus nerve iscomprised of A, B, and C fiber subtypes, and the B and C subtypes havebeen implicated in mammalian heart rate regulation. The dissociabilityand lower activation threshold of vagal anti-inflammatory signalingallow us to hypothesize that the A fibers, which have the lowestactivation threshold and do not appear to participate in heart rateregulation, may fulfill the role of cholinergic anti-inflammatoryfibers.

We also showed that vagus nerve stimulation suppressed serum TNF levelseven when applied 48 hrs before LPS administration, which is comparableto the cholinergic suppression of TNF in vitro. Future studies willcontribute to revealing detailed mechanisms underlying this long-lastinganti-inflammatory efficacy. Current anti-inflammatory therapies, such asglucocorticoids, are associated with serious side effects, includinghyperglycemia and immune cell apoptosis. We found that vagus nervestimulation does not reduce splenocyte viability, while glucocorticoidssignificantly deplete viable splenocytes, suggesting that vagus nervestimulation may be less toxic to the spleen. Vagus nerve stimulationalso significantly lowers serum glucose levels during systemicinflammation. Recent studies have demonstrated the adverse effects ofhyperglycemia in critically ill patients and the improvement in outcomethat results from tighter glycemic control.

The description above may be readily generalized to describe variousparameters and effects for vagus nerve stimulation that are new and veryunexpected. In particular, the extremely low level of stimulation (bothlow intensity, and low duty-cycle) have been seen to have a profound—andchronic—effect on the immune response. By low duty-cycle effect, we arereferring to the time stimulation is “on” compared to the timestimulation is “off” (e.g., the ratio of “on” to “off”). Thus, thestimulation (and particularly chronic stimulation) described herein is“off” much more that in it is “on”. The high efficacy of these lowduty-cycle modulation parameters is unexpected, and may have a profoundeffect on the way that treatment of immune response (humor and/orcellular) are performed. For example, chronic (or long-term) stimulationmay be effectively performed without the risk of negative effectsassociated with known stimulation protocols of the vagus nerve.

Furthermore, the low-intensity (and low duty cycle) situation may beused safely without interfering with other aspects controlled by thevagus nerve. For example, altered heart rate and blood pressure are notseen with the low-intensity, low duty-cycle modality stimulation. Thus,the vagus nerve may be stimulated either mechanically or electrically ina low-intensity and low duty-cycle fashion without desensitizing thevagus nerve or its targets, and without invoking a potentially unwantedphysiological effect (e.g., on heart rate, heart tone, blood pressure,gastric processes, or any other effect attributed to vagal nervestimulation except the targeted immune response).

Finally, the disclosure here may be used to support mechanicalstimulation and electrical stimulation modalities. For example,implantable mechanical and implantable electrical stimulators may beused having low-intensity and low duty-cycle stimulation protocols, asdescribed. Stimulation of the vagus nerve may be performed externally orinternally.

While the methods, systems and devices described above have beenparticularly shown and described with references to preferredembodiments thereof, it will be understood by those skilled in the artthat various changes in form and details may be made therein withoutdeparting from the scope of the invention encompassed by the appendedclaims.

What is claimed is:
 1. A method of treating an inflammation in apatient, the method comprising: stimulating, in a patient suffering frominflammation, the patient's vagus nerve with an electrical signal toachieve a therapeutic effect for treating the inflammation, wherein thesignal current is from 1 mA to 100 mA, the signal voltage is from 0.01Volts to 5 Volts, the pulse width is from 0.1 ms to 5 ms, the signalfrequency is from 0.1 Hz to 30 Hz, and the signal on-time is from 1second to 120 seconds, wherein the stimulation is transcutaneousstimulation of the vagus nerve; limiting the stimulation of the vagusnerve to a frequency of between 0.1 Hz and 30 Hz; and re-stimulating, bytranscutaneous stimulation, the patient's vagus nerve after waiting foran off-time of at least 2 hours and prior to dissipation of thetherapeutic effect for treating the inflammation, wherein thetherapeutic effect persists for at least 2 hours after stimulation hasended.
 2. The method of claim 1 wherein the off-time before the vagusnerve is re-stimulated is from 2 hours to 24 hours.
 3. The method ofclaim 1, wherein the off-time before the vagus nerve is re-stimulated isbetween about 16 and about 30 hours.
 4. The method of claim 1, furthercomprising monitoring the effect of the stimulation on inflammation inthe patient.
 5. The method of claim 1, further comprising determiningthe level of a pro-inflammatory cytokine prior to stimulation.
 6. Themethod of claim 1, wherein the signal current is between 1 mA to 5 mA.7. The method of claim 1, wherein the therapeutic effect is dissipatedby 72 hours after stimulation has ended.
 8. The method of claim 1,wherein stimulating comprises stimulating in a patient suffering frominflammation due to rheumatoid arthritis.
 9. A method of treatinginflammation in a patient, the method comprising: applying an electrodeto a patient suffering from a chronic inflammatory disorder;stimulating, by transcutaneous stimulation, in the patient sufferingfrom inflammation the patient's vagus nerve with an electrical signalfrom the electrode to achieve a therapeutic effect for treating theinflammation, wherein the signal current is from 1 mA to 100 mA, pulsewidth is from 0.1 ms to 5 ms; signal frequency is from 0.1 Hz to 30 Hz;signal on-time is from 1 second to 120 seconds; limiting the stimulationof the vagus nerve to a frequency of between 0.1 Hz and 30 Hz; andre-stimulating, by transcutaneous stimulation, the patient's vagus nerveafter waiting for an off-time of at least 2 hours and prior todissipation of the therapeutic effect for treating the inflammation,wherein the therapeutic effect persists for at least 2 hours afterstimulation has ended.
 10. The method of claim 9, wherein the chronicinflammatory disorder is selected from the group consisting ofappendicitis, peptic ulcer, gastric ulcer, duodenal ulcer, peritonitis,pancreatitis, ulcerative colitis, pseudomembranous colitis, acutecolitis, ischemic colitis, diverticulitis, epiglottitis, achalasia,cholangitis, cholecystitits, hepatitis, Crohn's disease, enteritis,Whipple's disease, allergy, anaphylactic shock, immune complex disease,organ ischemia, reperfusion injury, organ necrosis, hay fever, sepsis,septicemia, endotoxic shock, cachexia, hyperpyrexia, eosinophilicgranuloma, granulomatosis, sarcoidosis, septic abortion, epididymitis,vaginitis, prostatitis, urethritis, bronchitis, emphysema, rhinitis,pneumonitis, pneumotransmicroscopicsilicovolcanoconiosis, alvealitis,bronchiolitis, pharyngitis, pleurisy, sinusitis, influenza, respiratorysyncytial virus infection, HIV infection, hepatitis B virus infection,hepatitis C virus infection, disseminated bacteremia, Dengue fever,candidiasis, malaria, filariasis, amebiasis, hydatid cysts, burns,dermatitis, dermatomyositis, sunburn, urticaria, warts, wheals,vasulitis, angiitis, endocarditis, arteritis, atherosclerosis,thrombophlebitis, pericarditis, myocarditis, myocardial ischemia,periarteritis nodosa, rheumatic fever, Alzheimer's disease, coeliacdisease, congestive heart failure, adult respiratory distress syndrome,meningitis, encephalitis, multiple sclerosis, cerebral infarction,cerebral embolism, Guillame-Barre syndrome, neuritis, neuralgia, spinalcord injury, paralysis, uveitis, arthritides, arthralgias,osteomyelitis, fasciitis, Paget's disease, gout, periodontal disease,rheumatoid arthritis, synovitis, myasthenia gravis, thyroiditis,systemic lupus erythematosis, Goodpasture's syndrome, Behcet's syndrome,allograft rejection, graft-versus-host disease, Type I diabetes,ankylosing spondylitis, Berger's disease, Reiter's syndrome andHodgkin's disease.
 11. The method of claim 9 wherein the off-time beforethe vagus nerve is re-stimulated is from 2 hours to 24 hours.
 12. Themethod of claim 9, wherein the off-time before the vagus nerve isre-stimulated is between about 16 and about 30 hours.
 13. The method ofclaim 9, further comprising monitoring the effect of the stimulation oninflammation in the patient.
 14. The method of claim 9, furthercomprising determining the level of a pro-inflammatory cytokine prior tostimulation.
 15. The method of claim 9, wherein the chronic inflammatorydisorder is rheumatoid arthritis.
 16. A method of treating aninflammation in a patient, the method comprising: stimulating, in apatient suffering from inflammation, the patient's vagus nerve bytranscutaneous simulation, with an electrical signal to achieve atherapeutic effect for treating the inflammation, wherein the signalcurrent is from 1 mA to 100 mA, the signal voltage is from 0.01 Volts to5 Volts, the pulse width is from 0.1 ms to 5 ms, the signal frequency isfrom 0.1 Hz to 30 Hz, and the signal on-time is from 1 second to 120seconds; limiting the stimulation of the vagus nerve to a frequency ofbetween 0.1 Hz and 30 Hz; and re-stimulating the patient's vagus nerveby transcutaneous stimulation, after waiting for an off-time of at least2 hours and prior to dissipation of the therapeutic effect for treatingthe inflammation, wherein the therapeutic effect persists for at least 2hours after stimulation has ended, wherein the duration of the signalon-time is less than 1% of the duration of the signal off-time.
 17. Themethod of claim 16, wherein stimulating comprises stimulating in apatient suffering from inflammation due to rheumatoid arthritis.